package com.example.demo.zaqizabatest;

import java.io.RandomAccessFile;

/**
 * ******************************************************
 *
 * @author liugh9
 * @version 1.0
 * @classname RandomFileTest
 * @description
 * @date 2023/04/18 10:02
 * <p>
 * ******************************************************
 */
public class RandomFileTest {
    public static void main(String[] args) throws Exception {
        Employee e1 = new Employee("zhangsan", 23);
        Employee e2 = new Employee("lisi", 24);
        Employee e3 = new Employee("wangwu", 25);
        RandomAccessFile ra = new RandomAccessFile("C:\\Users\\liuguihua\\Documents\\study\\test_file\\employee.txt", "rw");
        ra.write(e1.name.getBytes());
        ra.writeInt(e1.age);
        ra.write(e2.name.getBytes());
        ra.writeInt(e2.age);
        ra.write(e3.name.getBytes());
        ra.writeInt(e3.age);
        ra.close();
        RandomAccessFile raf = new RandomAccessFile("C:\\Users\\liuguihua\\Documents\\study\\test_file\\employee.txt", "r");
        int len = 8;
        raf.skipBytes(12);//跳过第一个员工的信息，其姓名8字节，年龄4字节
        System.out.println("第二个员工信息：");
        String str = "";
        for (int i = 0; i < len; i++) {
            str = str + (char) raf.readByte();
        }
        System.out.println("name:" + str);
        System.out.println("age:" + raf.readInt());
        System.out.println("第一个员工信息：");
        raf.seek(0);//将文件指针移动到文件开始位置
        str = "";
        for (int i = 0; i < len; i++) {
            str = str + (char) raf.readByte();
        }
        System.out.println("name:" + str);
        System.out.println("age:" + raf.readInt());
        System.out.println("第三个员工信息：");
        raf.skipBytes(12);//跳过第二个员工的信息
        str = "";
        for (int i = 0; i < len; i++) {
            str = str + (char) raf.readByte();
        }
        System.out.println("name:" + str);
        System.out.println("age:" + raf.readInt());
        raf.close();
    }
}

class Employee {
    String name;
    int age;
    final static int LEN = 8;

    public Employee(String name, int age) {
        if (name.length() > LEN) {
            name = name.substring(0, 8);
        } else {
            while (name.length() < LEN) {
                name = name + "\u0000";
            }
            this.name = name;
            this.age = age;
        }
    }
}
